[The recovery of the sleep-wakefulness cycle during arousal from hibernation in the long-tailed Arctic suslik Citellus parryi].

New data and analysis are presented concerning the recovery of the sleep cycle during onset of deep winter hibernation (T brain = 3 degrees C) and arousal from hibernation in the Arctic ground squirrel at temperatures of the brain 3-35 degrees C. It was shown that natural arousal from hibernation is associated with gradual development of the sleep phases on a basis of the resting forms which are typical of the lower level of development of the central nervous system in vertebrates.